More tests for Parsoid's beneift.

* One more wikitable fostered content test for this:
  https://gerrit.wikimedia.org/r/#/c/51170/

* Merged duplicate extlink test with another.

* Added another extlink text that tests RTing of space-separated
  link-text.

Change-Id: I4307bde61b186734f3706dc8940f47e015ec2bc5
Merge "More tests for Parsoid's beneift."